LOCAL ANISOTROPIC STRUCTURE IN AMORPHOUS BA-FE-O FILMS AND ITS ROLE IN DETERMINING MAGNETIC-ANISOTROPY IN CRYSTALLIZED BA-HEXAFERRITE FILMS

Ba hexaferrite films with the easy direction of magnetization perpendi cular or in-plane can be prepared by crystalization of amorphous films deposited under different sputtering conditions. Using polarization-d ependent EXAFS (extended x-ray absorption fine structure), we have obs erved anisotropic local structure around the Fe atoms in as-sputtered amorphous Ba-Fe-O films. Such structure has not been detectable by con ventional structural characterization techniques (x-ray diffraction, e lectron diffraction and transmission electron microscopy [TEM]). The r esults suggest that this local structural anisotrophy determines the o rientation of the fast-growing basal plane directions during post-depo sition annealing and thus the directions of the c-axes and the magneti c anisotropy.